This invention generally relates to the generation and detection of non-binary digital sequences as applied in communications and other applications. The aspect of using binary digital sequences in applications such as wireless communications and watermarking is well known.
In wireless communication systems, such as CDMA, specific binary sequences, comprising a series of elements or chips representing 0s and 1s are used to code individual digital signals, representing the data to be transmitted, in a spread spectrum fashion. A sequence of binary element represents an individual 0 or a 1. When a system comprises a plurality of users, correct transmission of data requires that each individual transmitter is assigned a unique set of sequences representing a 0 and a 1. Presently, the sequences will still be binary sequences. Systems could also apply multi-coding wherein each user can transmit (and receive) sequences in such a fashion that each sequence represents a multi-state symbol. For instance, in 3-state spread spectrum coding, one may assign unique sequences to a user wherein a sequence represents the symbol 0, 1 or 2.
The application of sequences in for instance a wireless communications system may involve a plurality of users. Such a system requires the use of a set of sequences, wherein the sequences should have adequate individual characteristics. One of those characteristics may be the auto-correlation of a sequence. Another characteristic for distinguishing purposes between sequences may be the cross-correlation properties.
One of the present methods to detect the presence of a particular sequence in a received sequence is by generating a local copy of such a sequence and to compare this local sequence with an equal length part of the received signal.
In view of the limited present capabilities to generate desirable multi-valued digital sequences, there is a need for an easier method to create multi-valued digital sequences. There is also a need for creating new sets of multi-valued digital sequences. There is also a need for an easier detection method and new communication systems using the new sequences.